From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753235Ab1GZBZh (ORCPT ); Mon, 25 Jul 2011 21:25:37 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:51198 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752455Ab1GZBZ3 (ORCPT ); Mon, 25 Jul 2011 21:25:29 -0400 Message-ID: <4E2E178B.3000500@cn.fujitsu.com> Date: Tue, 26 Jul 2011 09:25:31 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.9) Gecko/20100921 Fedora/3.1.4-1.fc14 Thunderbird/3.1.4 MIME-Version: 1.0 To: Paul Menage CC: Frederic Weisbecker , LKML , Andrew Morton , Johannes Weiner , Aditya Kali Subject: Re: [PATCH 7/7] cgroups: Add a max number of tasks subsystem References: <1310393706-321-1-git-send-email-fweisbec@gmail.com> <1310393706-321-8-git-send-email-fweisbec@gmail.com> In-Reply-To: X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-07-26 09:24:34, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-07-26 09:24:34, Serialize complete at 2011-07-26 09:24:34 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paul Menage wrote: > On Mon, Jul 11, 2011 at 7:15 AM, Frederic Weisbecker wrote: >> /* */ >> + >> +#ifdef CONFIG_CGROUP_MAX_TASKS >> +SUBSYS(max_tasks) >> +#endif > > I think I'd be inclined to make the naming slightly (IMO) cleaner: > call the subsystem 'tasks' and the files 'limit' and 'count' (or maybe > 'usage' to be more in line with memcg). >> >> +config CGROUP_MAX_TASKS >> + bool "Control max number of tasks in a cgroup" >> + depends on RESOURCE_COUNTERS >> + help >> + This option let the user to set up an upper bound allowed number >> + of tasks. >> + > > Needs to depend on CGROUPS too? > it's done implicitly, because it's inside "menuconfig CGROUPS". >> + >> + >> +struct task_counter { >> + struct res_counter res; >> + struct cgroup_subsys_state css; >> +}; > > All other CSS structures put the "css" field as the first thing in the > structure. Not sure that anything relies on that, but consistency no as far as I know, and that's a bad thing. > can't hurt and it probably makes the code fractionally smaller since > the translation between CSS and task_counter becomes a no-op. > >> +static void task_counter_exit(struct cgroup_subsys *ss, struct cgroup *cgrp, >> + struct cgroup *old_cgrp, struct task_struct *task) >> +{ >> + struct task_counter *cnt = cgroup_task_counter(old_cgrp); >> + >> + if (cnt != &root_counter) >> + res_counter_uncharge_until(&cnt->res, &root_counter.res, 1); >> +} > > Do we even need the root_counter to be exposed in any way? Why not > make children of the root cgroup just have a NULL parent res_counter? > > You'll still need a task_counter object so that the cgroups framework > has a CSS object for cgroups housekeeping, but I don't think it needs > to actually be used for anything. > > Paul >